>>717340097
Lots of animals nest.
Beavers eat the soft outer layers of the trees. So getting larger pieces of wood are dual purpose.
Like many rodents their teeth evolved to gnaw cut and scrape. Some traits are just taken to an extreme niche because it was successful, like the giraffes neck.
It took billions of years for earth to even get simple life, then a billion more years to get mammals, then another hundreds of millions of years for the variety of mammals we have today.